Safety brake combination for pneumatic drills



L. J. MORIN July 6, 1965 SAFETY BRAKE COMBINATION FOR PNEUMATIC DRILLS 2 Sheets-Sheet 1 Filed Jan. 16, 1962 INVEN TOR. MWFf/Vff J NOR/IV United States Patent 3,193,055 SAFETY BRAKE COMBINATIQN FQR PNEUMATIC DRILLS Lawrence J. Morin, R0. Box 1284, Sierra Vista, Ariz. Filed Jan. 16, 1962, Ser. No. 166,529 4 Claims. (Cl. 1821-96) My invention relates to a safety brake combination for pneumatic drills. It relates more in particular to the safety braking of the reciprocating piston rod in a pneumatic drill of the type used in mining operations and frequently going by the name of stinger or jack leg stinger.

. rests on the floor or a support raised from the floor, and

which jack leg stinger is then moved over at an angle in the direction of the drift or stope into which the holes are to be drilled. Commonly, therefore, the holes are drilled at an angle and the tool is at an angle to the face in which the hole is being drilled, and the jack leg stinger is at an angle to the floor or raised support which takes it off the floor. While stingers may vary in detail of construction, they all have the characteristic that they are driven by compressed air and the tool-supporting shaft is reciprocated longitudinally of the stinger by a reciprocating piston. Because of this arrangement the tool is driven vertically with considerable force and in accordance with applicable mechanical principles the cylinder forming a part of the stinger is pushed in a reverse direction at the same force. If there is any slipping, therefore, of either the stinger or tool, the stinger shaft will be driven forwardly its full length and the stinger cylinder backwardly the same length, depending upon how slippage occurs, with consequent damage to equipment and frequent injury to workers. Attempts have been made to eliminate the hazard created by this condition, but they have not been successful because of the need to provide for full functional utility of the stinger equipment itself. In other words, suggestions heretofore made have been unsuccessful for various reasons, in part at least because they impaired the efficiency of the functioning drill equipment including the stinger.

The principal object of my invention is accordingly the provision of improved means for braking the actuating shaft of pneumatic drills of the type identified.

Another object is to provide an improved air leg brake combination.

A further object is the provision of an improved safety brake for a jack leg stinger which will not impede the drilling function of such stinger in normal use.

A still further object is the provision of an improved brake combination for the purpose described which is relatively light in weight and which adds relatively little percentage-wise to the total weight of the drill combination.

Other specific objects and features of the invention will be apparent from the following detailed description taken with the accompanying drawings, wherein:

FIG. 1 is a perspective view showing the safety brake of the present invention associated functionally with a jack leg stinger, the jack leg stinger being shown in broken lines;

FIG. 2 is an enlarged fragmentary sectional view "ice partly in elevation to show structural features, and with the figure broken in two parts to accommodate it to the size of the ofiicial drawing sheet;

FIG. 3 is a transverse sectional view taken on the line 3-3 of FIG. 2 looking in the direction of the arrows;

FIG. 4 is a transverse sectional view taken on the line 44 of FIG. 2;

FIG. 5 is a transverse sectional view taken on the line 5-5 of FIG. 2, and

FIG. 6 is a perspective view showing a detail of the ball check valve-retaining ring.

The safety brake device of the present invention is indicated generally in FIG. 1 by the reference character 10, and it utilizes an outer cylinder 11, a piston rod 12 and valve stem 13, as shown particularly in FIG. 2. The safety brake device It is adapted to be functionally associated with a stinger indicated generally by the reference character 15 and having an outer cylinder 16 within which the piston assembly (not shown) is longitudinally reciprocable to longitudinally reciprocate a shaft 17. The stinger 15 may be of any usual type and size and the safety brake device of the present invention is modified slightly so far as may be necessary to accommodate it to the particular stinger with which it is employed. The stinger shown in the drawings is of a type known as the Gardner Denver, but equipment devices of the same kind are made by others. The stinger has the usual chicken leg support 18 designed, of course, to permit its being supported at an angle and leaned in the direction of a face in which holes are to be drilled vertically without slipping.

The cylinders 11 and 16 are secured together by a pair of cylinder clamps 19. These clamps may be of various types, but they should be so constructed that they will firmly hold the safety jacket, as my device may be called, to the jack leg stinger with which it is to be associated. In the drawings I show the clamps as having a relatively solid hexagonal portion into which the cylinder 11 fits fairly sungly with positive attachment provided for by means of Allen type set screws 21. The clamps are shown split to pass around the cylinder 16 and they may be clamped to the cylinder 16 by nuts and bolts 22, one of which appears in the drawing.

A piston rod clamp indicated generally by the reference character 23 comprises the parts 24 and 26 clamped together around the piston rods 12 and 17 by bolts 27. As indicated by the right hand side of FIG. 2 the rods may have exterior rings fitting in annular recesses in the clamp members 24 and 26 to avoid any possible slippage between the piston rod and piston rod clamps.

Before referring to further details of the safety brake combination of the present invention I wish to point out that the function obtained is to permit normal actuation of the jack leg stinger in accordance with the particular kind of face against which the drilling is occurring, and to permit free return movement of the jack leg stinger piston under all circumstances, but to limit the movement of the jack leg stinger beyond that normally required for functional operation so that, if there should be any slippage, the jack leg stinger will not be forceably elongated beyond its functional movement in drilling, so that in this way violent expansive movement of the drill and/or stinger foot is prevented and injuryto equipment and personnel avoided.

Referring now particularly to FIG. 2, the cylinder 11 is closed at its bottom by a plug 28 welded in position so that no leakage can occur. It is closed at its top by a cap 29 held in position by cap screws 31. The cap screws 31 are anchored in a piston rod stuffing box frame 32 having a bottom extension 33 threaded into the top ing :42.

of the cylinder ill, as shown particularly in FIG. 2.. An

anchoring pin 34 has a press fit in a hole drilledgen-j.

' erally tangent to the pitch line of the threads between the cylinder 11 and the portion 33, the anchoring pin 34 then being pushed into position in the general manner shown in- FIG. 3. V

The piston rod Estufiing'box assembly is, of

course, so designed and assembled that-hydraulic fluid in'the cylinder ll will-not leak out. One seal is provided by an A O-ring 36 placed-between the end of the cylinder 11 and shoulder on the stuffing box frame 32. Within the stufiing box Lprovide threeO-rings 37. in contact with the piston rod 12 separated by seal1rings'38; and the 1 entireasse'mbly; held down by a retainer 39 held in positionby machine screws .41.] Above the retainerr39-and between such'retainer and .the cap .29 there is suitable annular packing .42 .which may, forzexample, be Johns- .Manville interlockedpacking. "A suitable thickness, of shim 43 may be placed between the capv 29 and the pack- At the, bottom end of the cylinder 11 and attached to the pistonrod 12 is a piston head assembly indicated generally by-thereference character 45. This piston head assemblyincludes a frame portion '46,; the top of which has internal threads 47 for attachment to external threads on a smaller diameter portion of the piston rod 12. This structure provides a shoulder on the piston rod which engages against the end of the piston head assembly frame 9 :46 and provides forfirm attachment. Tohold the piston head assembly to the piston rod, however,- I provide an anchoring 'pin d of suitable design.

When thesafety brake device of the present invention is A operating, the entire cylinder 11 is filled with oil :and

-there is acontr-olled dash-pot type arrangement which permits the oil to move from one side of the pistonhead gassemblyto the other. The controls aresuch that when thepistomhead assembly.is moving upwardly in the cylinder the flow is somewhat restricted. in accordance with the setting. of va control, but'in whichthere is free return movement/The .rnechanism-associated in part with the piston head assembly provides for. the necessary functioning andcontrolp V I V A pair of suction washers. 49 areseparatedby afls'pacer l openings 63,'however, are normally closed by ball valves 64 held in place by a retaining ring 66' (see FIG. 6). The arrangement of the ball valve 64 is such that when the cylinder head assembly is moved upwardly they will be retained on their seats and will restrict the flow of hydraulic fluid to. them which will pass through the radial openings 59; but when the movement is downwardly,. or' on a return. stroke of the piston rod and stinger rod shaft, hydraulic flow is,un restricted.

As the drawings also (show, the valve stem 13 has a rounded bottom end 67 which. functions as a 'valve with the shoulder formed between the central recess 57 and gtheienlarged.portioni58. The extent to which'the valve 67 is spaced from its seat, therefore, determines how freely hydraulic fluid will flow at this point, and it in :fillfl'l iscontrolled by means of ayalve stern adjusting nut 68. This valve stem adjusting nut 68 forms part of a top assembly including a valve stem stufiingboxarrangement, which will now be described.

Referring to the top portion of the right hand side of FIG. 2,; a frame for the valye stem stufiing box indicated generally by the reference character 69 has a downwardly extending skirt '7ll, an upwardly extending skirt 72, and

an integral central disc-like portion 73. The skirt 71 is threaded and engages'in the top internalthreads on the piston rodri2, ansO-ring- 74; being interposed between the top oft he piston rod'12-and the. bottom of the portion '73. When :themember 69-has been turned to proper position by threading its-skirt 71 into the topthreaded gogportion of the piston rod a set screw '76 is placed in position-to-hold. thezparts in permanent assernbly. It will be seen-from the drawings-thatthe valve stem 13 extends through the stulhng box and, in general, the clear- -.ances are:such.as to, permit a relativelyfreerotational movernentof the valve stem with respect to the piston rod.

Within the shirt 72 and between, its inside annular fsurface .andihe valve stem lirl place 'a pair of O,-rings 77 [separated by a spacer 78 and with the entire assembly held .togetherbya shouldered retainer 79 which is threaded into the upper'part of the skirtr72. .An O-ring 81 is disposed between the shoulder on the retainer 79 and the 7 ,upper annular edge of the skirt 72., A suitable set screw, as shown, is provided between the skirt,72 and retainer 79 51, and the assembly comprising these two suctionwash-- ers and spacer abut up against ashoulder 52. They are held against the shoulderby. a' relatively large diameter washer 53 11rged upwardly by a lock'washer 54, and

itheentire assembly secured in placeby a pair of jam nuts 56. The suctionywashers are made. of suitable material, such as relatively soft rubber, thattheir fiared out peripheries will ride against the inside surface of the wardly The suction washers 49, however,

tional construction. As the drawings show, the frame memberdti is. provided with a central longitudinal open- ,to hold the twofirmly in the relation established during preliminary assembly thereof.' 7

The adjusting nut 68 has a bottom exteriorly threaded .skirt which engages outer threads onthe skirt 72 of the frame .69, such thatwhen the adjusting nut 68 is turned it a will move up and down vertically with respect to the entire assemblytincluding the pistonrod. The adjusting nut 68 is rigidly secured to the valve stem 13 at the top thereof by a weld portion 82,.hence, by rotating the adjusting nut 68,

i the valve stem 13 may be raised orrlowered and the positionof the valve .67 with respect to its seat controlled. The

adjusting nut 68 carries a positioning pin 83 spring-pressed downwardlyland vertically in the direction of the disc-like portion'73, This disc portion has a plurality of top re- 7 cesses 841(FIG. 4) into which the bottom end of the posibut tends to seal against the inside of the cylinder when the movement is upwardly.

do not provide the 7 basic control for the piston head assembly, but this control is accomplished with exactitude with still an addi-" ing 57 provided withvan upper enlargement 58. A plurality .of radial openings 59 connect the enlarged space 58 with the exterior of the piston head assembly above the suction washer-s 49. V nular recess 61 with which a plurality of verticalholes The frame ddalso has an antioning pin 83, which is rounded, is adaptedto project.

This produces. a click.action in that the positioning pin will .dropiintoa recess and certain set positions of the valve stem can be recognized by -,the operatorfor the proper control, of'his mechanism.

.Althoughthe number of positions of the valve stem may .vary;.I indicate; in the drawings a total of five positions in onev of which the valve stem will be adjusted to closed position, and in the others of which it Would-be adjusted ,to successively larger openings of the valve 67 for different types ofadvance and for different types of work. At the first position after closed, for-example, the advance of the stingerpermitted by the adjustment'would be for slow. 'In positions '2, 3 and 4 the actuation of the 62 and annular openings 63 communicate, theopenings 63 providing'a communication between the central longitudial opening 57 and the annular recess 61. The

stinger tool would-be soft,- medium-and hard respectively, andat position 5 the device would be entirely open. The adjustments are controlled in accordance with the hardnesscharacteristics of the material through which the drilling is taking place. The purpose is to permit free forward movement of the stinger in accordance with its usual functioning, but to provide a brake when it has travelled forwardly a suflicient distance to accomplish its function in the particular environment in which the tool is working at a given time. In using the safety brake of the present invention, therefore, all that is necessary is to attach it to a hydraulic tool 15 in the manner shown in PEG. 1, adjust the nut 68 in accordance with the work being performed, and proceed in the ordinary way to accomplish the safe drilling of the multiple holes to which the operator is assigned. If at any time there is a slippage or any action where the tool and chicken foot are not firmly in place, there will be no unimpeded movement of the rod 17 such as to cause injury to equipment and personnel. The device of the present invention does not impede the free movement of the worker in any significant manner. In a jack rod assembly weighing one hundred and thirty pounds, for example, the device of the present invention will add approximately only six pounds. Those skilled in the art are aware of the fact that pneumatic tools of the type preferred to commonly have a handle at a point intermediate its ends, so that the tool can be carried by one hand in a balanced position. Under such circumstances the balance can be provided in the same manner for the safety brake of the present invention, and the entire manner of handling the tool is practically unchanged.

Those skilled in the art will understand that the present invention is not limited to the exact structural features shown, it being only necessary that a generally similarly functioning structure be provided. The tools shown in the drawings and described in the specification, therefore, are not limiting, and the scope of the invention is defined by the claims.

I claim:

1. A jack leg stinger safety brake comprising, a cylinder and a piston rod, a piston head connected to said piston rod, means defining a longitudinal opening extending through said piston head and having an enlarged portion to form a valve seat, means defining a radial opening communicating with said longitudinal opening for providing a fluid flow path through said piston head, a valve stem extending through said longitudinal opening, said valve stem formed to mate with said seat, means defining an annular recess below said valve seat communicating with said longitudinal opening, means defining a hole parallel to said longitudinal opening communicating with said annular recess to provide a second fluid flow path through said piston head, and a ball valve positioned withing said annular recess to permit fluid flow in said second fluid flow path in only one direction.

2. A jack leg stinger safety brake comprising, a cylinder and a piston rod, a piston head connected to the piston rod, means defining a longitudinal opening extending through said piston head and having an enlarged portion to form a valve seat, means defining a plurality of radial openings communicating with said longitudinal opening to provide a fluid flow path through said piston head, a valve stem adjustably extending through said longitudinal opening, said valve stem terminating in a rounded tip formed to mate with said seat, means defining an annular recess below said valve seat communicating with said longitudinal opening, means defining a plurality of holes parallel to said longitudinal opening each communicating with said annular recess to provide a plurality of second fluid flow paths through said piston head, a plurality of ball valves positioned within said annular recess to permit fluid flow in said second fluid flow paths in only one direction.

3. The device defined by claim 1 having a suction Washer mounted on said piston head and engaging the inside walls of said cylinder below said annular recess for permitting fluid flow past said piston head during a return stroke and preventing fluid flow past said piston head during a power stroke. I

4. A device defined by claim 2 having a suction washer mounted on said piston head and engaging the inside walls of said cylinder below said annular recess for permitting fluid flow past said piston head during a return stroke and pl'effiting fluid fiow past said piston head during a power stro 'e.

References Cited by the Examiner UNITED STATES PATENTS 1,171,085 2/16 Beck 251-54 1,219,035 3/17 Pettengil 188-88502 1,939,200 12/33 Brady 188-962 2,130,939 9/38 Williams 188-962 2,132,519 10/38 Slater 121-9 2,301,318 11/42 Peo 251-54 2,337,738 12/43 Christensen 188-88502 2,657,595 11/53 Shaif 121 2,674,098 4/54 Taylor 121 2,918,248 12/ 59 Schoenrock 251-54 2,991,760 7/61 Rhine 121 3,039,443 6/62 Hay 121-9 ARTHUR L. LA POINT, Primary Examiner.

KENNETH J. ALBRECHT, Examiner. 

1. A JACK LEG STINGER SAFETY BRAKE COMPRISING, A CYLINDER AND A PISTON ROD, A PISTON HEAD CONNECTED TO SAID PISTON ROD, MEANS DEFINING A LONGITUDINAL OPENING EXTENDING THROUGH SAID PISTON HEAD AND HAVING AN ENLARGED PORTION TO FORM A VALVE SEAT MEANS DEFINING A RADIAL OPENING COMMUNICATING WITH SAID LONGITUDINAL OPENING FOR PROVIDING A FLUID FLOW PATH THROUGH SAID PISTON HEAD, A VALVE STEM EXTENDING THROUGH SAID LONGITUDINAL OPENING, SAID VALVE STEM FORMED TO MATE WITH SAID SEAT, MEANS DEFINING AN ANNULAR RECESS BELOW SAID VALVE SEAT COMMUNICATING WITH SAID LONGITUDINAL OPENING, MEANS DEFINING A HOLE PARALLEL TO SAID LONGITUDINAL OPENING COMMUNICATING WITH SAID ANNULAR RECESS TO PROVIDE A SECOND FLUID FLOW PATH THROUGH SAID PISTON HEAD, AND A BALL VALVE POSITIONED WITHING SAID ANNULAR RECESS TO PERMIT FLUID FLOW IN SAID SECOND FLUID FLOW PATH IN ONLY ONE DIRECTION. 